ArduinoJson

Arduino JSON library

A simple and efficient JSON library for embedded systems.

It's design to be very lightweight, works without any allocation on the heap (no malloc).

It has been written with Arduino in mind, but it isn't linked to Arduino libraries so you can use this library in any other C++ project.

Features

• JSON decoding: more details here
• JSON encoding: more details here
• Elegant API, very easy to use
• Fixed memory allocation (no malloc)
• Small footprint
• MIT License

Feature comparison

Library	Memory allocation	Nested objects	Encoding	Parser size	Encoder size
Arduino JSON	static	yes	yes	2616 Bytes	896 bytes
json-arduino	dynamic	no	no	3348 (+28%)	N/A
aJson	dynamic	yes	yes	5088 (+94%)	4678 (+419%)

Parser size was measured with a program parsing {"sensor":"outdoor","value":25.6}. For each library, I wrote a program that extracts a string and a float. I subtracted the size of a program doing the same without any JSON parsing involved. Source files are here.

Encoder size was measured with a program generating {"sensor":"outdoor","value":25.6}. Source files are here.

In each case the target platform was an Arduino Duemilanove and Arduino IDE 1.0.5 was used.

Links: json-arduino, aJson

Testimonials

From Arduino's Forum user jflaplante:

I tried the [aJson and json-arduino] before trying your library. I always ran into memory problem after a while. I have no such problem so far with your library. It is working perfectly with my web services.

From Arduino's Forum user gbathree:

Thanks so much - this is an awesome library! If you want to see what we're doing with it - the project is located at www.photosynq.org.

From StackOverflow user thegreendroid:

It has a really elegant, simple API and it works like a charm on embedded and Windows/Linux platforms. We recently started using this on an embedded project and I can vouch for its quality.

Links

• The project for which I made me this library
• Blog post on the motivation for this library